As communication terminals are manufactured to have a portable size, the communication terminals are used in a variety of fields due to their easy availability and portability. Recently, these communication terminals have developed into smartphones equipped with a variety of user functions, and thus can provide convenience and entertainment.
Along with the wide use of smartphones, users are using a variety of user functions, especially a variety of smartphone-based communication services. For example, typical users use chatting services with their smartphone, use specific web services, or use services for exchanging emails with others. In this case, a user operates a variety of smartphone-based applications to use a specific communication service. However, in order to use a specific communication service provided by each application, the user should perform a sign-on to a service server that supports operation of the corresponding application, to receive a confirmation that the user is a rightful user to acquire use authority. The sign-on is necessary for each smartphone user to secure and use a normal communication service.
However the sign-on may often cause the user inconvenience. For more detailed description, in order to use a specific application-based communication service, the user should communicate sign-on information with each service server, and thus perform the sign-on. In this case, unfortunately, the sign-on may force the user to repetitively input sign-on information under an inconvenient input condition when there are increasingly various kinds of applications or when a user should input the sign-on information in a limited screen state. Furthermore, when the sign-on information is differently set for each application, a user should input the sign-on information for each application. In this case, when the user cannot remember the sign-on information correctly, the user should input incorrect sign-on information and thus perform an additional correction procedure. Frequently, this inconvenience causes many users to stop using a specific terminal-based communication service.